PB2070: EFFICACY OF RITUXIMAB MAINTENANCE THERAPY IN ADVANCED-STAGE FOLLICULAR LYMPHOMA: A SINGLE-CENTER RETROSPECTIVE STUDY.
Authors: C. Amorós, O. Mompel, P. López-Menargues, C. Játiva, A. Cámara, R. García-Serra, M. J. Lis-Chulvi, M. E. López-Pavía, C. Villegas-Da Ros, M. Linares-García
Journal: HemaSphere (2022)

Background: Previous studies have established that 2-year rituximab (RTX) maintenance after induction treatment improved progression-free survival (PFS) in patients with advanced follicular lymphoma, although without evidence of effects on overall survival (OS). However, the effectivity in routine clinical practice should be confirmed. Aims: The primary goal of the present study was the assess the effect of RTX maintenance on clinical outcomes (OS and PFS) and study its prognostic impact in patients with advanced disease. Methods: We conducted a comprehensive single-center retrospective analysis of outcomes of 88 advanced FL patients, treated between January 2005 and February 2021. We selected patients that had obtained a complete (CR) or partial response (PR) after induction therapy regardless of follow-up with RTX maintenance. Baseline data collected included the following: age, sex, FLIPI stage, hemoglobin level, lymphocyte and platelet count, serum LDH and beta-2 microglobulin level. Continuous variables were compared with Mann-Whitney U test, and categorical using Chi-square or Fisher´s exact tests. PFS and OS were estimated using the method of Kaplan-Meier and compared with the log-rank test. Prognostic factors for PFS and OS were determined per Cox regression analysis. Results: Patients´ median age was 60,5 years; 58% were female. 63 patients received induction therapy with R-CHOP, 8 with R-CVP and 17 with bendamustine-R. Overall, 54 of the selected patients started rituximab maintenance and 34 continued follow-up only with clinical observation. The rates of CR and PR were 81.5% and 18.5% in the maintenance group and 73.5% and 26.5% in the observation group. There were no significant differences among the prognostic variables at diagnosis (Table 1). In the observation group, more patients progressed (58.2% vs 24.7% in maintenance group) and more received second-line treatment (44,1% vs 24.1%). After a median follow-up of 60 months, 19 patients (21,6%) had died. RTX maintenance therapy showed a significant benefit in both PFS and OS, compared with observation (Table 2). Multivariant analysis showed that age (HR 1.063; 95% CI: 1.015-1.105; p=0.010), lymphocyte count (HR 1,049; CI 1.01701-1.083; p=0.003), LDH (HR 1.001; CI 1.001-1.002; p<0,001) and RTX maintenance (HR 0.193; CI 0.061-0.612; p=0.005) were independent prognostic factors for OS. Regarding PFS, the only independent variables were response to induction-therapy CR vs PR (HR 0.084; CI 0.038-0.187; p<0.001) and RTX maintenance (HR 0.251; CI 0.110-0.577; p=0.001). Table 1. - Diagnostic variables Maintenance Observation p Age 60 (35-84) 63 (38-85) 0,070 Hemoglobin 13,05 (7,7-17) 13 (9,1-15,4) 0,627 Lymphocyte 1,4 (0-53) 1,4 (0-54) 0,888 Platelet 195 (55-442) 226 (91-516) 0,227 Beta-2 microglobulin 2172 (254-6321) 2650 (222- 7727) 0,077 LDH 386 (229-3817) 421 (242-3054) 0,115 Sex (M/F) 22/32 15/19 0,826 FLIPI High: 34 (63%) 23 (67,6%) 0,896 Intermediate: 15 (27,8%) 8 (23,5%) Low: 5 (9,3%) 3 (8,8%) Table 2. - Maintenance Observation p PFS Median not achieved 127 months (24 – 229) 0,017 At 2 years: 92% At 2 years: 75,8% OS Median not achieved 132 months (111-152) 0,003 At 2 years: 95,9% At 2 years: 85,3% At 5 years: 92,6% At 5 years: 69,4% Image:Summary/Conclusion: RTX maintenance following induction therapy provided a significant long-term PFS, concordant with previous studies. Meanwhile, respect the OS, it has shown significant benefit unlike previously published, probably due to differences in the characteristics of our study: older patients, more advanced-stage patients, and lower intensity second-line therapy.